Osteoporosis increases the risk of fracture and has become a significant public health threat nowadays in the world. It is very important to diagnose osteoporosis in a very early stage. Quantitative Ultrasound (QUS) has become a widely available non-invasive tool for assessment of bone status and diagnosis of osteoporosis.
There are mainly three approaches for QUS measurement in the prior art.
The first approach is based on the axial transmission mode (cf. U.S. Pat. No. 7,112,173 B1, U.S. Pat. No. 7,022,076 B1, U.S. Pat. No. 6,221,019 B1). Representative commercial devices include Omnisense 7000 and Omnisense 8000 (BeamMed Ltd, Israel). As shown in FIG. 1a, a pair of probes 900, 901 are placed in tandem on one side of the bone 196. The axial transmission mode is suitable for assessing long bones such as tibia and radius. Here a tibia ultrasound assessment device is used as an example. The pair of probes 900, 901 are fixed on a bracket (not shown) which is connected to a pedal (not shown) on which a subject can stand. When the subject stands on the pedal, the pair of probes 900, 901 are in tandem on one side of the tibia.
The second approach is based on the transverse transmission mode. Representative commercial devices include Express (GE®, US), SONOST-3000 (Osteosys®, Korea), Osteo Pro (BMTECH®, Korea). As shown in FIG. 1b, which is a side view of a bone, and FIG. 1c, which is a corresponding profile taken on the line AA′ in FIG. 1b, a pair of probes 900, 901 are placed in opposite direction across the bone 196. The transverse transmission mode is suitable for status evaluation of cancellous bones such as the heel pad (cf. Patent No. US2003/0068014 A1, U.S. Pat. No. 6,676,291 B2), bone thickness measurement (cf. U.S. Pat. No. 7,537,566 B2) and age evaluation (cf. U.S. Pat. No. 7,678,049B2). The bracket and pedal structure may be similar to that used for the axial transmission mode.
The third approach is based on the pulse-echo mode. Related technologies include ultrasound critical-angle reflectometry (UCR) (cf. Patent No. US20050015010; U.S. Pat. No. 6,899,680) and backscattering techniques (cf. Patent No. US20020161300). The pulse-echo mode takes advantage of wave reflection or scattering at the soft tissue-bone and cortical-trabecular bone interface, and is able to assess bone material properties and microstructures. As seen in FIG. 1d, a probe 900 transmits an ultrasound signal to the bone 196 and receives an echo signal of the ultrasound signal from the bone 196. The bracket and pedal structure may be similar to that used for the axial transmission mode.
WO 2011/119873 A2 discloses ultrasound guided automated wireless distraction osteogenesis, wherein the ultrasound transceivers are mounted to the bone, subcutaneously on two sides of the osteotomy.